Electrical connector for twin lead-in line



Nov. 4, 1958 A. HYMAN 2,859,423

ELECTRICAL CONNECTOR FOR TWIN LEAD-IN LINE Filed April 6, 1954 a 1451:2144: HVMA: 1 4 6. J

ATTORNEY United States Patent ELECTRICAL CONNECTOR FOR TWIN LEAD-IN LINE Abraham Hyman, New York, N. Y.

Application April 6, 1954, Serial No. 421,371

1 Claim. (Cl. 339-97) My invention relates to an improved electrical connector terminal block for twin lead-in lines particularly suitable for home television and frequency modulation apparatus.

Electrical connector terminal blocks now available vary widely in design and size to meet the various needs of specific television installations. These standard terminal blocks are designed for operation with a particular type of television lead-in line. There are at least four standard types of television lead-in lines in use. Consequently, each popular standard terminal block is made in various models or designs to accommodate the different type of lines. This is economically undesirable for the manufacturer and the television installer because it calls for large inventories.

It is therefore an object of my invention to provide a novel design for an electrical connector terminal block that will accommodate operation with any type of standard lead-in line. A single, standard terminal block operable with all of the standard television lines in use will result in economy because it will decrease inventories and simplify the manufacture of terminal blocks.

As a further object and advantage of the instant invention, the improved connector terminal block readily admits the incorporation of a lightning arrestor circuit including fuse means for the protection of the operation of the television receiver over UHF and VHF television bands. For example, and as illustrated herein, the circuit is made up of fuses, resistors and coils. The fuses provide the protection against atmospheric voltage or current surges. A specially designed coil in series with each fuse provides marked neutralization of stray capacitances in the UHF band. A high resistance element across the input of the terminal block, joined at a center tap to a grounding post offers the desirable leakage path for static charges.

Further objects and advantages will become apparent from the following description and figures in which:

Fig. 1 is a perspective view of an electrical connector terminal block incorporating my novel raceway design and illustrated with a ribbon type twin lead connected to K one end of the terminal block and an open wire twin lead connected to the other end;

Fig. 2 is a bottom view of the terminal block showing the novel arrestor circuit;

Figs. 3 and 4 are sectional views taken, respectively, along lines 33 and 4-4 of Fig. 2;

Fig. 5 is an end view of the terminal block showing a tubular type of twin lead connected thereto;

Fig. 6 is a sectional view taken along line 66 of Fig. 2;

Fig. 7 is a perspective view of a short piece of ovalshaped twin lead conductor; and

Fig. 8 is a perspective view of a saw-tooth washer.

Electrical connector terminal block 10 has a chassishousing 11 made of hard, electrical non-conducting material, such as porcelain or synthetic resin. Housing 11 'ice is an elongated rectangular-shaped parallelepiped having a top surface 25, a smooth continuous end and side wall 29, 43 and a recessed bottom surface 30.

One feature of my invention is the novel raceway adaptable to operate with any one of the four differently shaped standard lead-in conductorsv To meet this object, the ends of top surface 25 by means of recessed ledges, grooves, and a semi-circular undercut are designed in a novel manner to provide an arrestor raceway design that accommodates connections with any one of the standard but differently shaped lead-in conductors.

There are four types of conductors now being used as standard television lead-in lines. The ribbon type twin lead 31 is the conventional parallel, two wire line shown connected to one end of arrestor 10 in Fig. l. Ribbon line 31 consists of two wires 32, 33, which may be stranded, spaced apart and embedded along the opposite longitudinal edges of a flat ribbon of synthetic plastic. The tubular type twin lead line 34, note Fig. 5, and the oval type twin lead line 35, Fig. 7, are essentially modifications of ribbon line 31. For tubular line 34, two parallel wires 61, 62, which may be stranded, are embedded in a length of synthetic plastic having a circular cross-section. Fig. 5 shows tubular line 34 connected to one end of terminal block 10. Wires 61, 62 are embedded in diametrically opposite sides of the insulation and extend parallel to the axis of the tubular body of insulation. Oval shaped line 35 differs from tubular line 34 only in that the insulator cross-section of the former is oval in shape. For oval shaped line 35, the parallel pair of leads are embedded at opposite ends of the semi-major axis. The fourth type of line accommodated by my terminal block is the open wire line 36. Fig. 1 illustrates the connection of line 36 to one end of terminal block 10. Line 36 consists of two bared solid wires 63, 64 held in fixed parallel relationship by insulator bars 37 spaced along line 36.

Terminal block 10 is inserted into the lead-in line connecting the antenna to the television receiver. Accordingly, one end of terminal block 10 is connected to the antenna side whereas the other end terminal block is connected to the receiver side.

With respect to the raceway design, both ends of terminal block 10 are identical; accordingly, it is essential to describe only one end.

The lead-in line is fastened and electrically connected to terminal block 10 by means of a pair of electrically conductive washers 28 located at each end of terminal block 10. Washers 28 are fastened to terminal block 10 in the region of the raceways. Washer 28 has a circular fiat top surface 44, a concentric opening 51 and a downwardly projected annular serrated saw-tooth rim 45. The saw-tooth serrations of rim 45 are caused to pierce the insulation of the lead-in line and are thus brought into electrical contact with the wires thereof. Washers 28 are mounted on a pair of threaded terminal posts 39, 40. Post 39 is to the left of axis 26 and post 40 is to the right thereof. One washer is mounted on each post. Hexagonal nuts 50 threadedly engage the terminal posts 39, 40 on top of washers 28 and thus provide the means for clamping and maintaining the washers in electrical contacting relationship with the wires of the lead-in conductor.

The raceway consists of a semi-circular recess 20, a pair of ledges 21, 22 and a pair of grooves 23, 47. Semieircular recess 20 is located between posts 39, 40. Recess 20 extends longitudinally into housing 11 from end wall 29 to a terminating wall 27. Wall 27 defines a plane normal to axis 26. The distance from posts 39, 40 to wall 27 along axis 26 is chosen to allow adequate clearance to facilitate insertion and clamping of the lead-in line. A pair of flat ledges 21, 22 coextend in parallel relationship on diametrically opposite sides of recess 20- and terminate at wall 27. Ledge 21 is to the left of recess 20; ledge 22 is to the 'right thereof. Ledges 21, 22 are recessed downwardly from surface -25 to form a step s'hapedcontour in cross-section with surface 25. The depth of ledges 21, 22 from surface 25 is approximately equal to the height of saw-tooth rim 45;

Apair of grooves 23, 47 extend longitudinally into housing 11, a convenient and arbitrary distance past posts 39, 40. Grooves 23, 47 are recessed downwardly from surfacej25 a depth equal to the depth of the recessed ledges21, 22. Grooves 23, 47 coextend in parallel relationship, respectively, to the left of and to the right of posts'39, 40. Circular recesses 41, 42 are located betweenthe forward and rear sections of grooves 23, 47. Washers '28 are seated in recesses 41, 42. The diameter of recesses 41, 42 is slightly larger than washers 28 to assure the necessary clearance so that the latter can be easilyseated in the former.

.Grooves 23, 47, recesses 41, 42 and ledges 21, 22 all a'r'erecessed downwardly from top surface 25 the same depth. Thus, these recessed portions of housing 11 form a; continuous flat surface on either side of recess 20 clearly illustrated in Fig. 4. Terminal posts 39, 40 are predetermina'tely located on either side of recess 20 so that the inner and outer peripheral portions of the saw-tooth rims 45 of the seated washers 28 engage the flat surfaces of the adjacent grooves and ledges.

It has been established that both ends of terminal block 'are.designed with clamping washers 28 and raceways composed of recesses, ledges and grooves to receive the different types of lead-in lines. From the standpoint of theraceway design, either end of terminal block 10 may be connected to the antenna side of the circuit. However, the arrester circuit makes it preferable to connect one side .to the antenna for reasons explained hereinafter. The other end is then available for connection to the receiver.

A pair of fuses 16, 17 laterally disposed about axis 26 are carried in undercuts 46 at top surface 25. Fuse 16 is to the left of axis 26; fuse 17 is to the right of axis 26. Fuses '16, 17 are removably clamped by conventional resilient clamps which themselves are fastened to housing 11 by means of threaded bolts 48, 49.

g- A; threaded .bolt 24 is located at the center of housing 11. The head thereof is withdrawn below surface 25 within the surrounding undercut. Bolts 24, 39, 40, 48 and 49 pass through the floors of their correlated recesses and undercuts. Bottom surface 30 of housing 11 is rege ssed deeply and surrounded by a thick wall 52 along the periphery of housing 11. Bolts 48 and 49 are terminated close to surface 30 and engage hexagonal nuts at surface 30. Bolt 24 extends past surface 30 but not beyond the plane of edge 53 of thick wall 52. Ahexagonal nut at surface 30 holds bolt 24. Terminal lugs are mounted on the exposed ends of bolts 24, 48 and 49 which bolts are fastened securely to the housing 11 by the aforementioned means. Compared to the others, bolts or posts 39, 40 are reversed and extend up- 'wardly. Although not necessary, each post is supplied with 'an engaging nut 65 withdrawn below recesses 41, 42 in undercuts covered by washers 2 8. Nut 65 holds the posts to the recess while nuts 50'are disengaged. Bolts 39, 40 also carry lugs 54 at bottom surface 30.

' Grooves 23, 47 are predeterminedly spaced apart laterally about axis 26' the same distance between 'wires 63, 64 of'the standard open line. Connection of an open wire. line is effected by inserting each wire 63, 64in a 'corielated groove 23, 47. The wires are held to the terinitial block by the clamping action of washers 2 8. Ledges 21, 22 are predeterminedly spaced apart laterally about axis 26 a distance approximately equal to the distance between the wires 32, 33 of a standard ribbon line. This assures that wires 32, 33 are adequately supv 4 the ledge raceway. The line is clamped by washers 2.8. Boththe tubular and oval type of lead-in lines are inserted into the ledge and recess 20 raceway with the wires 61, 62 thereof in a horizontal plane to assure contact with the washers upon clamping same into the line. Recess 20 serves as clearance to receive the deformed under portion of the tubular or oval line when it is clamped to the terminal block. For this purpose recess 20 in the preferred embodiment has an /s radius. Upon clamping, wires 61, 62 are supported by ledges 21, 22. The arrester circuit consists of a coil and fuse connected in series relationship with each wire of the twin lead line. The circuit also includes high resistance elements connected between a common grounding post, bolt 24, and each wire of the twin lead line. In the illustrated embodiment, coil 14 and fuse 16 are in series relationship with one side of a twin-lead line; whereas, coil 15 and fuse 17 are in series relationship with the other wire of the lead-in line. Coils 14, 15 are mounted on the recessed bottom surface 30. At the receiver end of terminal block 10, coil 14 is connected between post 39 and bolt 48. On the other side of fuse 16', the antenna side of terminal block 10, bolt 48 is connected to terminal post 39 and also' to one end of resistor 12. The actual connection is made by soldering the lugs 54 thereof to a terminal of resistor 12. The other end of resistor 12 is connected to grounding post 24. Coil 15 is connected between post 40 and bolt 48. On the other side of fuse 17, the bolt 49 is connected to terminal post 40 and also to one end of resistor 13. The other end of resistor 13 is connected to grounding post 24. The essential factor of the arrester circuit is the series relationship of the coil and fuse, which are, as a combination, in series relationship with a wire of the twin lead line. Accordingly, from the standpoint of electrical connections coils 14, 15 may be on either side of fuses 16, 17. However, to obtain the full benefit of the static discharge circuit, it is preferable that leakage resistances 12, 13 are on the input or antenna side of terminal block 10.

In the illustrated embodiment, coils 14, 15 each consist of 3 /2 turns of #21 copper wire wound to form a coil having approximately a /s' diameter. The coils minimize the stray capacitance effects of the hardware elements, such as the nuts, bolts, clamps and fuses of the arrester in the UHF band of operation. Although the design of the coils may be varied to provide better results for specific UHF stations, the aforesaid specifications provide the optimum results over the complete UHF band of television channels. Each leakage resistor 12, 13 is 2.2 megohms to present a high impedance to the 300 ohm twin lead line and thus avoids loading the line.

'1 For desirable operation fuses 16, 17 are conventional li amp 250 volt elements, commercially known as type 3AG fuses.

The cavity formed by the recessed botom surface 30 and wall 52 is partly filled with a mass of pitch, wax or anyv suitable non-conductive mastic, note Fig. 6, to act as a waterproof seal and a protective coating for the internal wiring of terminal block 10. Grounding post 24 is sufiiciently long to project through the sealing element and is connected by any conventional means (not shown) to a good ground.

-Suitable means such as top-to-bottom openings 56 are provided to receive screws or bolts (not shown) for mounting terminal block 10.

The foregoing description illustrates an embodiment of my invention; as such, this description should not be taken in any limiting sense but as an illustrative example of the invention.

What is claimed is:

A terminal block for twin lead in lines comprising,-

an electrical non-conducting body, parallelepiped in shape, having an end-face-to-end-face longitudinal axis,

said body having a top surface equipped with a raceway at each end thereof, a pair of terminal posts mounted on said body in the region of each raceway, and a washer engaged to each terminal and having a rim of downwardly projecting saw-teeth, each of said raceways having a curvilinear recess, a pair of ledges, a pair of washer undercuts, and a pair of grooves, said recess projecting downwardly from said top surface and extending longitudinally along said axis from an end face of said body to a terminating wall, said wall lying in a plane perpendicular to said axis, each ledge of said pair being at an opposite ledge of said recess and projecting downwardly from said top surface to efiect a step shape in cross-sec tion, said ledges extending longitudinally from the end face of said body and terminating at said wall, one pair of posts being located intermediate said end face and said wall with each post of said pair adjacent a correlated ledge, each washer undercut surrounding a correlated post and being adapted to seat the washer engaged thereon, said undercut communicating with the ledge adjacent thereto whereby the inner side of the washer rim is able to project onto the surface of the adjacent ledge, said grooves projecting downwardly from said top surface and being longitudinally parallel to said axis from said end face to a point beyond said posts, each of said grooves extending along the outer side of a correlated post and communicating with the undercut thereat whereby the outer side of the saw-tooth rim of the washer engaged by said correlated post projects onto the bottom surface of said groove, whereby said washers co-operate with the surrounding raceway to effect electrical connection with and clamping of a twin-lead line inserted into said raceway.

References Cited in the file of this patent UNITED STATES PATENTS 1,093,477 Rudenberg Apr. 14, 1914 1,303,383 Osborne May 13, 1919 1,728,534 Fortescue Sept. 17, 1929 2,291,468 Golde July 28, 1942 2,584,476 Liaci Feb. 5, 1952 2,654,857 Finkel Oct. 6, 1953 2,666,908 Klostermann Jan. 19, 1954 2,728,896 Aleks Dec. 27, 1955 2,742,549 Peters Apr. 17, 1956 

